Heat exchanger



Nov. 18, 19.41. J p; RATHBUN 2,263,397..

HEAT EKCHANGER' Filed June 22, 1940 INVI INTOR JOHN E Raw-Haw.

. BY 9' /5.M

as ATTORNEY Patented Nov. 18, 1941 HEAT EXCHANGER John P. Rathbun, Prospect Park, Pa., assignor to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsylvania Application rune 22, 1940, Serial No. 341,821

2 Claims. (oi. 257-28) The invention relates to heat exchangers, more particularly to heat exchangers having a desuperheating section, and has for an object the prevention of any condensing action occurring in such desuperheating section.

Another object of the invention is the provision of means for controlling the transition point between the condensing and desuperheating sections of heat exchangers.

These and other objects are effected by my invention as will be apparent from the following description and claims taken in connection with the accompanying drawing, forming a part of this application, in which:

Fig. 1 is a vertical sectional view taken through a heat exchanger embodying the invention; and,

Fig. 2 is a transverse sectional view taken along the line IIII of Fig. 1, looking in the direction of the arrows. i

In a heat exchanger or feedwater heater in which the last tube pass is segregated for a desuperheating section, so as to raise the flnal feed temperature'to or above the saturated steam temperature, it is frequently important to' control the transition point between the condensing section and the desuperheating section.

This is particularly important when it is necessary for installation reasons to have the stationary tube plate downward, with the heater in a vertical position. Under such conditions, the

' combination of tube sizes which will permit regulating the amount of surface in the last tube pass without going to excessive water velocities. By this means, it is possible to utilize all of this pass as a desuperheating section and establish a transition point therebeyond, thereby preventing condensate. from draining into the desuperheating section.

Referring now to the drawing more in detail, there is shown a heat exchanger comprised by a vertically-disposed shell l having a steam inlet II and a condensate outlet l2, both near the bottom thereof. A plurality of tubes l3 and 14 extend longitudinally of the shell and are supported by a fixed tube plate l5 at the lower end of the shell and a movable tube plate H5 at the portion of the floating head l8 which has a cover l9 held in closing relation thereto by suitable means, such as the bolts'20.

Where the heat exchanger is of the four-pass type, as herein illustrated,'the floating head constitutes a reversing water box and is provided with a transverse partition 2|. Preferably, the upper end of the shell i0 is closed by the cover 22, provided with 'a flange 23 adapted to be secured to the corresponding flange 24 on the shell III by suitable means, such as the bolts 25. The lower end of the shell is provided with a flange 2! adapted to abut the upper side of the fixed tube plate IS, the lower-side of the tube plate being engaged by a corresponding flange 28 carried by the water box 29. Suitable means, such as bolts or welding, are relied upon for retaining flanges 2'! and 28 and the tube plate l5 in assembled relation. The water box 29 is provided with an inlet conduit 30 and a discharge conduit 3!, together with transverse partitions 32 which, in cooperation with the parcondensing section 38, the bailie 34 preferably tubes thereof, the tubes I 4 in the desuperheating section 35 are of materially, larger size than the tubes l3 in the condensingsection 36. This difference in tube sizes assures that the transition point between the desuperheating and the condensing sections of the apparatus falls outside of the desuperheating section. Obviously, if any condensation occurred within the desuperheating section, the moisture collecting on the tubes H would flow down the latter, thereby defeating the purpose of this section.

In order to insure tortuous flow of steam through the apparatus to obtain maximum ex change of heat, baflies 38 and 39 are provided in the desuperheating and condensing sections, respectively'.

While the invention has been illustrated as applied to a vertical feedwater heater, it will be upper end, the movable tube plate forming a apparent that features and advantages thereof maybe highly desirable in horizontal heat changers. v

While I have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various changes and modifications without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are specifically set forth in the appended claims.

What I claim is:

l. A heat exchanger comprising a vertical shell having a vapor inlet and a condensate outlet, a plurality of tubes extending longitudinally through said shell and defining a plurality of water passes, upper and lower tube plates supporting the ends of said tubes, water boxes associated with said tube plates, and a bafile structure extending upwardly from said lower tube plate with its upper end spaced from the upper tube plate and having its bottom and side edges sealed with respect to the bottom tube plate and the sides of the shell, respectively, said baflle structure and shell defining a desuperheating section containing the tubes of the last water pass and a condensing section containing the remaining tubes, the tubes in said desuperheating section beingmaterially larger than the tubes in said condensing section, whereby lowering of the temperature of vapor in the desuperheating section'will be limited.

2. A heat exchanger comprising a' vertical shell having a vapor inlet and a condensate outlet, a plurality of tubes extending longitudinally through said shell and defining a plurality of water passes, upper and lower tube plates supporting the ends of said tubes, water boxes associated with said tube plates, and a bafile structure extending upwardly from said lower tube plate with its upper end spaced from the upper tube plate, the baflle structure and the shell defining a desuperheating section containing the tubes of the last water pass and the condensing section containing the remaining tubes, the tubes in said desuperheating section being materially larger than the tubes in said condensing section, whereby lowering of the temperature of vapor in the desuperheating section will be limited.

JOHN- P. RATI-IBUN. 

